1. Field of the Invention
This invention relates generally to water sprinklers and is particularly concerned with the nozzles of sprinkler heads for distributing water over a predetermined pattern on the surrounding ground.
2. Description of Related Art
Water sprinkler or spray heads are typically mounted on submerged water supply pipes at desired locations over an area to be watered. Such heads may be of the travelling type which swing from side to side or rotate in order to move a spray of water to cover an area to be sprinkled. Other heads are fixed to provide a specific spray pattern, such as a quarter circle, half circle or full circle. However, such fixed heads allow only one specific spray pattern, which may not conform to the desired watering area. Thus, such heads have to be replaced with one of different design if it is necessary to change the spray pattern.
Adjustable sprinkler heads are also known, which allow the spray pattern to be varied on installation, so that a single fixed spray head has the capability of providing various different spraying patterns. However, these are subject to some disadvantages in that they do not provide full range adjustability, and are sometimes inconvenient to adjust. For example, U.S. Pat. No. 4,739,934 of Gewelber describes a sprinkler head moulded with a large number of identical small orifices which are initially plugged by light barriers. In order to produce a desired spray pattern, the barriers closing the selected orifices must be punctured. Once punctured, an orifice cannot subsequently be re-closed, limiting the degree of adjustability. Additionally, the punctured barriers produce spurs in the orifice which may disturb or plug the spray. Also, this head is relatively inconvenient and awkward to adjust where a wide angle spray pattern is desired, in view of the large number of barriers which must be punctured.
U.S. Pat. No. 3,830,434 of Green et al. describes another adjustable sprinkler head having four identical orifices. This does not provide a wide range of variation, nor is a full 360 degree spray possible with this sprinkler head. Also, each orifice is associated with a valve member for controlling the flow to that orifice between a fully closed and fully open position. Thus, the spray range from each orifice must be controlled separately. Alteration of the valve opening to one orifice will alter the range from any other open orifices, necessitating repeated adjustment of the valve members when spray from more than one orifice is required. This is particularly inconvenient where the spray head must be removed from the riser pipe for access to the valve members. Additionally, it is extremely difficult, if not impossible, to provide matched precipitation rates from each orifice in this nozzle when adjusted. In other words, for a given flow rate, the amount of water actually sprayed from each orifice will not be matched with the other orifices, so that different areas will receive different amounts of watering.